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New 645M, bad altitude data!

Darren-M
over 6 years ago
My wife's 645M was supposed to be an upgrade from the Vivoactive HR. However, her first run today got the altitude so wrong it's not fit for purpose. The run started at +20 feet above see level, from a position in the street away from the house. the run was relatively flat, with no more than about a 30ft min/max elevation. The 645M recorded the had the elevation between min/max at 25ft, which I'd guess is somewhere near correct, but the lowest point was recorded as -226ft. which is an error of -246ft and is obviously unacceptable. When the GPS locks and grabs the altitude it should be no less accurate than around +/- 80 - 100ft, and that's based on GPS satellites on a bad day! The Vivoactive HR was pretty accurate with usually only 10ft errors or so. However, it also appears to have produced bigger (nowhere near that of the 645M though) altitude errors since the second half of December. Has there been an update since the middle of December? Does anyone else know of any current issues with the latest firmware or the 645M watch?
  • 0 over 5 years ago in reply to Roedema

    Any update to this ? is there no way out but to buy another watch ? Replacing it does not seem to have solved anything. Exercising now is even more important in these lockdown times.

  • 0 over 5 years ago in reply to enetnut

    The altimeter of my 645 generally produces reasonable results. For example, across dozens of runs along the same 3.1 mile route, the ascent is always 100 ± 10 ft. Temperature swings do cause more variation on longer routes. One thing I haven't seen mentioned in this thread, but which has come up in other threads about the altimeter, is clearing the two little ports on the side of the watch. These holes let air in to the barometer. Dunk your watch in a bit of soapy water. Stick a pin in there (not too deep) if you have to.

  • 0 over 5 years ago in reply to enetnut

    I did some tests for Garmin support where I cycled & ran the same route & sent them the data. Cycle version was pancake flat, run produced a sawtooth elevation graph. Never heard anything back so assume they're not interested as the 645 is pretty much a dead product now. We'd probably have seen the 655 by now except for the Covid-19 pandemic.

    Personally I've given up on it ever working!

  • 0 over 5 years ago in reply to jkissane_

    the barometer is affected by temperature. pedaling and keeping the watch on the handlebar the temperature remains constant and the altitude is correct, when you run and hold your wrist the temperature is influenced by the heat of the Runner and the altitude has sudden and incorrect variations. Garmin should have designed the watch better by positioning the temperature sensor in a different position. I will return the watch to Amazon a month before the warranty expires if Garmin does not do something to fix it. I had purchased the 645 to use the power but in this way it is not usable

  • 0 over 4 years ago in reply to scotthunter2

    I wish I had found this pre my 645 purchase a year ago. Purchased for the altimeter function as one of the main reasons. Recently downloaded ABC via Connect to establish whether duff readings were the user or hard and software. The reading at the top of my stairs went from 46 to 22m in a day with no obedience if subsidence.

    Out on the hill I input the hill height from OS map. For done reason, GPS ceased and all went to pot tho visibility wise I was ok. What on earth is the point of this function if it can not be relied upon as a x check for location finding?

    Thanks

    Sonya

  • 0 over 4 years ago in reply to 3188122

    I'd long given up on this & just turned on the elevation correction in GC so it ignored the data from the watch. Since then I've sold my 645 & picked up a 945 & guess what no more sawtooth elevation graphs while running. 

  • 0 over 4 years ago in reply to jkissane_

    How do you activate that elevation correction? Thanks.

  • 0 over 4 years ago in reply to Thibaud J

    It's right there on the activity screen.

  • 0 over 4 years ago

    I have the same problem. The 645 barometric elevation is very bad. Had I known beforehand, I would not have bought it. Very sad, otherwise the watch is great. Apparently, Garmin fixed it in one of the firmware updates bu switching to GPS elevation once the barometer starts to jump. That's the worst possible solution, then there's no way to compensate jumps later, but you simply miss the data. GPS elevation is much worse than SRTM data from my region, so in practice I have a watch without barometric elevation. The reason I bought the 645 was because it has barometric elevation. Garmin, can you see the problem here? I frequently run with a Suunto tester. None of the six watches he wears for comparison simultaneously has such issues, not even in beta stage. If it had, they'd make sure to fix it before distributing it. I think my life-long Gamin affinity is coming to an end here...